Great ideas and I would give them a try, actually already have removed Out of supply card out from the deck). I don't know why even they put that strange card there as it represents random effect which you can use to harm your opponent and that is out of the usual logic of the C&C games. Usually the cards are used for manouvering your troops, giving them boosts or reacting to action of the opponent. Suddenly I can declare his spearhead unit "out of supply" and send it back to the rear, wtf? Or miracolously saving one of my units. It is like declaring thunderstorm resulting in loss of fire power, for me it does not make sence in game terms.
Speaking historically, I have come uppon an article on the french supply train which appeared to had been pretty well organised, Napoleon himself putting special emphasis on that. I believe that the "out of supply" motive had been used mainly as an excuse for early returning skirmishing missions and as an individual excuse for leaving the ranks.